Sensing Circuits and Transition Control Mechanisms for Soft-Switching Current Source Converters

Abstract

The Soft-Switching Solid-State Transformer (S4T) and the Soft-Switching Current Source Inverter (SSCSI) are two novel resonant transition converters with zero-voltage switching (ZVS) across the entire load range, benign failure modes, current source behavior for easy paralleling and scaling, and controlled dv/dt. While conventional modulation techniques, including Space Vector Modulation (SVM), can be readily adapted to these new topologies, the very fast dynamic underlying the resonant transitions and resonance sequence enabled by the resonant tank(s) require additional attention. This paper proposes two simple, reliable and ultra-fast sensing circuits together with robust control mechanisms to ensure proper timing and control of the resonant tank(s). With this new approach, device stress is mitigated even under larger converter transients or fault conditions, and the soft-switching operation is guaranteed, including in applications with wide variations of source and load voltages (e.g., motor drives) or for multi-port converters interfacing multiple sources and loads operating at different voltages and frequencies.